Highway bridge live loads

The National Association of Australian State Road Authorities (NAASRA) is currently rewriting the bridge design specification in limit states format, thus requiring a rational approach to the formulation of the design live loads. A direct simulation model, based on a 1979 truck mass survey is presented. Multiple presence of trucks, both in a single lane and for multilane elastic response of the bridge is then calculated by passing a train of loads across a set of influence lines. Bridges with up to four lanes, and up to three continuous spans can be analysed (a).